考虑材料时变性的服役中小跨径桥梁横向地震响应分析

Transverse Seismic Response Analysis of Small and Medium-span Highway Bridges in Service Considering Time-varying Characteristics of Materials

构件材料性能会随服役时间的增加而退化,并导致桥梁结构抗震性能存在时变性。为探讨不同服役期下中小跨径桥梁抗震性能变化规律,以3跨预应力混凝土连续桥梁为例,通过分析材料力学性能指标时变性,量化不同服役期构件力学分析模型参数,并考虑桥墩、挡块及支座等构件力学性能退化,采用OpenSees软件建立桥梁有限元分析模型。基于非线性时程分析结果,揭示服役中小跨径桥梁横桥向地震响应时变性。研究结果表明,随着服役时间的增加,材料力学性能发生退化,使中小跨径桥梁各构件抗震能力下降;相同水平地震作用下,中小跨径桥梁主梁及挡块位移响应随服役时间的增加而降低,而桥墩损伤程度加剧,构件震害程度与不考虑构件力学性能时变性时相差较大,其中板式橡胶支座刚度及摩擦系数时变性是关键。因此,在服役中小跨径桥梁抗震分析中,有必要同时考虑桥墩、挡块及支座力学性能退化。

As the service time of bridge components increases,their material properties degrade,leading to a time-dependent reduction in the seismic performance of the bridge.To investigate the variation in seismic performance of small-and medium-span highway bridges over time,a finite element analysis(FEA)was conducted using a three-span prestressed concrete continuous girder bridge as a case study.This study quantifies the time-varying mechanical properties of components,such as piers,shear keys,and laminated rubber bearings,by incorporating degradation effects into a mechanical analysis model.The bridge FEA model was developed using OpenSees,accounting for the deterioration of key structural elements over time.The analysis reveals that,as service time increases,the degradation of material properties results in a reduced seismic capacity for various components.Under the same seismic event,the displacement response of the main girder and shear key decreases with time,while the damage to the piers becomes more severe.The seismic damage patterns of these components,when accounting for time-varying mechanical properties,differ significantly from those observed without considering such degradation.One critical finding is that the time-dependent variation in stiffness and friction coefficient of laminated rubber bearings plays a crucial role in the overall seismic response.Therefore,in the seismic analysis of small-and medium-span highway bridges,it is essential to consider the concurrent degradation of mechanical properties in piers,shear keys,and laminated rubber bearings to accurately assess their long-term seismic performance.